Field of the Disclosure
The present patent application relates to a process and to an apparatus for producing a magnesium sheet from a magnesium strip in a rolling device.
Brief Description of Related Technology
The production of sheet magnesium is becoming increasingly important on account of the growing demand. In particular, it has been found that sheet magnesium is suitable for the production of vehicle bodies, the sheet magnesium having a relatively low weight combined with strength properties comparable with those of sheet aluminium.
However, the production of sheet magnesium is relatively complex compared to the production of sheet steel or sheet aluminium, since magnesium, owing to its hexagonal lattice structure, has poor deformation properties at the processing temperatures usually present during cold-rolling. To successfully produce sheet magnesium, it is therefore necessary to observe a defined temperature range lying approximately between 230° C. and 450° C.
Rolling devices for producing a magnesium strip are known in the prior art. By way of example, EP 2 478 974 A1 discloses a finish-rolling device for producing a thin magnesium strip, said finish-rolling device comprising a rolling stand for receiving two working rollers, defining a working gap, having a heating device, and also a preheating furnace for heating the magnesium strip. Furthermore, EP 2 478 974 A1 discloses a process for producing a thin magnesium strip in such a finish-rolling device.
DE 10 2006 036 224 A1 discloses a finish-rolling device for producing a magnesium strip, the operation of which involves the use of various measures for maintaining an elevated temperature level of the magnesium strip after it has entered into the finish-rolling device. Thus, for instance, the coiling devices of the finish-rolling device, which is operated in reversing mode, are provided with winding reels, these forming an outer housing of coiling mandrels, such that magnesium strip arranged on the coiling mandrel is covered by the winding reel, in order to minimize a temperature loss in the coiling device. Furthermore, a continuous furnace is arranged on the outlet side of the rolling stand and heats the magnesium sheet during operation. Owing to the heat losses which arise during operation of the roller, heating above the rolling temperature is necessary, but this has an adverse effect on the rolling stock.
DE 10 2004 023 885 A1 discloses a process for flexibly rolling magnesium strip or aluminium strip or magnesium panels or aluminium panels, in which process the strip material or the panel material is rolled out over the entire length from a starting thickness to a final thickness which varies over the length in the longitudinal direction of the rolling operation. If magnesium is used as the strip material or panel material, it is heated to a temperature of between 180° C. and 280° C. for hot-rolling.
In the known finish-rolling devices, the additional heating devices result in an increased outlay on installation and operation of the finish-rolling device, and this also concerns in particular the energy required for operating the finish-rolling device.